The research on institutionalization is interesting and not necessarily consistent with the linear link between time in the institution and later problems. We’re all so different — it’s hard to generalize and say that if your child spent their first two years in an orphanage, then you can expect to see A, B, and C. Also, orphanage care differs by country, by region, and even within the orphanage itself. Truth be told, we parents differ in our temperaments and preparation, and this affects our kids as well.
However, having said all that, the research does show some patterns that support what you’re seeing. Motor skill delays are usually the first to improve once a child is placed in a loving home, while language and social skills may lag behind. Research shows that many kids who spent time in an institution pre-adoption have some lingering language issues once school age.
I have a section on language development in adopted kids on my website—click on “Adoption,” then “Resources,” then “Language Development." Also, I just added a fact sheet on how post-institutionalized kids develop social skills and friendships to the “School Issues” section on the “Adoption Resources”page.
On a personal level, I started one of my sons a year late in school and never regretted it. It’s so common that he doesn’t stand out or feel particularly different, although he does complain when an older grade gets privileges that his grade doesn’t.